Traffic signal lights control traffic by use of a green light for "GO", an amber light for "CAUTION" and a red light for "STOP". Most traffic lights are directed at oncoming traffic, and some traffic lights even employ shields, so that the light from the traffic light cannot be easily seen by motorists traveling in alternate directions. This is done so that motorist traveling in alternate directions do not anticipate when a traffic light is about to change. Most traffic signal lights incorporate a momentary delay when cycling between stop and go, to allow motorists time to clear the intersection. Some motorists enter the intersection after the amber turns to red, in an attempt to pass through the intersection before cross traffic enters the intersection. This is a dangerous practice that leads to accidents, injury and sometimes death.
Police routinely monitor motorist compliance, to ensure safe driving practices. A patrol car must be positioned to view the traffic signal light, so that the patrolman can accurately determine compliance with traffic laws. Because the traffic light is only visible to oncoming traffic, the patrol car must be positioned to view the traffic signal light, which means the patrol car must pass through a red light to stop a motorists who runs a red light. This is dangerous, not only to the patrolman in the patrol car, but also to other motorists crossing the intersection with the green light. It is especially dangerous where the patrol car is parked, and must accelerate rapidly to catch the traffic violator.
Attempts have been made to signal the patrolman at a location other than in position to view the traffic signal from an oncoming position. This equipment has proven to be expensive to install and maintain.
Therefore, what is needed is an inexpensive means to allow a patrolman to monitor traffic signal activity from an adjacent road, or behind the traffic signal.